CHICAGO — Music festivals are all about "you totally had to be there" moments that only happen when 80,000 people get together for three days of music. And Lollapalooza 2013 was no different, with countless amazing memories provided by everyone from Nine Inch Nails to Kendrick Lamar, Mumford & Sons, Lana Del Rey, Haim and Icona Pop, among others.

Sunday's roster included daytime sets from sister act Tegan and Sara, British buzz band Alt-J, rapper 2 Chainz and Vampire Weekend. They helped close things down on a 72-hour blitz of strange, wonderful and funny moments that MTV News witnessed on the ground.

10 awesome things you missed at Lollapalooza:

Recipe for success: Kendrick Lamar told Chicago it was the "livest city" he's played on tour and he didn't scrimp on the energy during his set on Saturday. The amped audience provided him with a moment when, during "The Recipe," they lifted up a man in a wheelchair on their hands, which totally caught Kendrick's attention mid-song. "Oh s---, look at that dude in the wheelchair!" he said. "Ya'll some crazy mother---ers!" He took a break a short time later to give the crowd time to bring that man and another in a wheelchair up to the pit in front of the stage.

He wasn't alone in his wonder, because on Sunday night in the middle of a show that featured his "Beez in the Trap" and "Bandz a Make Her Dance" verses, as well as "I Luv Dem Strippers" and "Duffel Bag Boy," rapper 2 Chainz was blown away by the very same visual. "That's the dopest s--- I ever seen in my mother---in' life, put him in the front row!" said Mr. "Feds Watching." He then led the crowd in a chant of "VIP! VIP!" as the hoisted the man into the photo pit.

A Bra, and an apology: When sister trio Haim played on the Grove Stage on Saturday, bassist Este Haim reminisced to guitar player/singer Danielle about the time they saw the Cold War Kids perform on the same stage in 2007, when she mused, "it would be cool if we were on that stage some day." Well, their dream came true, but not before Este had to apologize to her mom and dad (who were in the audience) for saying she wanted to make out with everyone in the crowed. "Lo siento ['I'm sorry'], mom and dad," she said with a grin.

She then thanked a fan for tossing a bra on stage in what the Haim's agreed was their first-ever in-concert underwear offering, which came in the middle of a set that offered their patented mix of blues, rock, soul and a little funk. "I feel you girl, just enough," she teased about the B-cup.

Things that should be banned at festivals:: Dudes wearing plastic SpongeBob inner tubes, full dress suits and banana costumes. Mullet dresses (long in the back, short in the front). Red, white and blue flag shorts, tights, tube tops, bandanas, hot pants, unitards, sunglasses, headbands and hats, we get it, you love America!

Mumford & Sons on "Fire": It was a challenge for the British folk rockers to keep their huge audience's attention during a largely acoustic main stage set on Saturday night. Near the end, singer Marcus Mumford tested those who hung in there with what he promised was a "very, very, very quiet" song that would require them to "shut the f--- up" for a few minutes.

And he wasn't kidding, as the band gathered around a single mic for a campfire jam-like cover of the Bruce Springsteen ballad "I'm On Fire" that would have been hard to hear under any circumstances, but was especially difficult over the roar of the masses.

Things that made no sense: The long-haired guy in all army green holding a basketball and bobbing his head to DJ rocker band Lance Herbstrong. The shocking amount of sailor hats and flowered garlands worn by women. Dudes in half shirts that expose their hairy bellies.

Sunshine of your love: After the threat of serious rain all morning on Friday, the drops started falling during Icona Pop's set on the Lake Shore stage. Then, the sun burst through for just a bit and the drops stopped just in time for their big hit, "I Love It."

Full Disclosure: English EDM duo Disclosure cracked up before an interview with MTV News at a condom advertisement being trailed behind a plane over their shoulder. "That's amazing!" said the Howard Lawrence to brother Guy about the flying safe-sex advert. "You would never see that in England!" The brothers then spent a minute laughing like schoolboys about the slogan behind the plane, "Can't wait to get it on."

Hot enough for you?: During their Sunday afternoon set, Tegan of Tegan and Sara said the pair were glad to be wearing jackets this year thanks to the balmy-for-Chicago 75 degree weather. She recalled that when the duo played Lolla in 2005, sister Sara got heat stroke. "I looked over and she left the stage and I had to finish the show (on my own)," Tegan said. This time, though, both were in fine voice, as they strummed through fan favorites like "The Con" and "Not Tonight," and "Closer."

Fan-tastic: Nothing is cooler than home made signs and Lollapalooza had some of the best ever. Our two favorites were an homage to troubled actress Amanda Bynes and a beautiful painting of Lana Del Rey. The latter was on display during the sad-eyed chanteuse's arresting set on Friday night, during which she took time out to greet her fans mid-show, sign autographs, pose for pictures and acknowledge the amazing likeness in the painting.

Surfing to Phoenix: Mope icons the Cure helped shut Lolla 2013 down with a hit parade of classics including "Lovesong," "In Between Days" "Just Like Heaven" and "Friday I'm In Love," which got fans from 18 to 58 doing a joyful goth pop boogie in the South field. Down at the other end French rockers Phoenix were equally shrouded in fog and alien landing-like stage lights, blasting through harder edge versions of favorites like "Entertainment" and new single "Trying to Be Cool."

Singer Thomas Mars ended the set by running through the audience to the soundboard and then crowd surfing his all the way back to the stage for the perfect capper to the weekend. Like a lot of the spent attendees, he was elated and exhausted, but it was 100 percent worth it.